1. Field of the Invention
This invention is directed to a combination catalyst having at least three difference catalyst components, and a process for using the same in a single stage operation for simultaneously hydrodewaxing and hydrotreating various petroleum residua.
2. Description of the Prior Art
Catalytic dewaxing of hydrocarbon oils to reduce the temperature at which separation of waxy hydrocarbons occurs is a known process. A process of that nature is described in The Oil and Gas Journal, dated Jan. 6, 1975, at pages 69-73. See also U.S. Pat. Nos. 3,668,113 and 3,894,938, which describe dewaxing followed by hydrofinishing.
U.S. Pat. No. Re. 28,398 describes a catalytic dewaxing process with a catalyst comprising a zeolite having a Constraint Index of 1 to 12. A hydrogenation/dehydrogenation component may be present.
A process for hydrodewaxing a gas oil with a zeolite having a Constraint Index of 1 to 12 is described in U.S. Pat. No. 3,956,102.
A Mordenite catalyst containing a Group VI or a Group VIII metal may be used to dewax a low viscosity index distillate from a waxy crude, as described in U.S. Pat. No. 4,110,056.
U.S. Pat. No. 3,755,138 describes a process for mild solvent dewaxing to remove high quality wax from a lube stock, which is then catalytically dewaxed to a specific pour point.
It is well known that many, if not most, petroleum base stocks contain contaminants, such as, for example, sulfur, nitrogen and metals. It is desirable, particularly if these feedstocks are to be further processed, that the contaminants be removed. This is an operation usually requiring the use of a catalyst. These feedstocks also usually contain waxy components which, because of the resultant high pour point, are difficult to pump and process. Thus, it is also desirable to reduce the amount of waxy component and to accordingly reduce the pour point of the feedstock.
It is well known in the art to effect sulfur removal from hydrocarbon stocks by subjecting them to treatment with hydrogen at elevated temperature and pressure while in contact with a catalyst containing hydrogenating components. Typically, the hydrogenating components of such prior art catalysts are Group IVA or Group VIII metals, or their oxides or sulfides. These hydrogenating components may be supported on a variety of well-known carriers, for example, alumina, kieselguhr, zeolitic molecular sieves and other materials having high surface areas; see in this regard U.S. Pat. No. 4,080,296. U.S. Pat. No. 3,546,103 teaches hydrodesulfurization with a catalyst which includes cobalt and molybdenum on an alumina base. U.S. Pat. No. 3,755,145 describes a process for preparing lube oils, characterized by low pour points, which utilizes a catalyst mixture comprising hydrogenationn components, a conventional cracking catalyst which can be either crystalline or amorphous and a crystalline aluminosilicate zeolite having a Constraint Index of 1 to 12.
U.S. Pat. No. 3,894,938 relates to the catalytic dewaxing and desulfurization of high pour point, high sulfur gas oils to lower their sulfur content by contacting such an oil with a ZSM-5 type zeolite hydrodewaxing catalyst having a Constraint Index of 1 to 12, which may contain a hydrogenation/dehydrogenation component, in the presence or absence of added hydrogen, followed by conventional hydrodesulfurization processing of the dewaxed intermediate.
Co-pending application Ser. No. 310,550, filed Oct. 13, 1981, discloses and claims a single stage operation for hydrotreating and hydrodewaxing petroleum residua using a dual catalyst system; that is, a hydrodesulfurization catalyst combined with a metal-containing ZSM-5 hydrodewaxing catalyst. This patent is hereby incorporated by reference.
U.S. Pat. No. 4,440,630 relates to a single stage catalyst system and process for using the system in a single stage operation for hydrodewaxing and hydrotreating petroleum residua. The catalyst comprises a ZSM-5 type zeolite in alumina binder having specified metal content and pore volume characteristics. This patent is hereby incorporated by reference.
U.S. Pat. Nos. 4,456,700 and 4,458,024 relate to a process for hydrodewaxing and hydrotreating petroleum residua to more valuable products. The catalyst system described in U.S. Pat. No. 4,458,024 includes a zeolite having a Constraint Index of 1 to 12, an alumina binder, at least one Group VIII metal selected from nickel, cobalt and iron, and at least one Group VIB metal. The catalyst is characterized by specific metals content and pore volume features. A related development is described in co-pending application Ser. No. 307,555, filed Oct. 1, 1981.
U.S. Pat. No. 4,225,421 describes a process for hydrodemetallation and hydrodesulfurization of a hydrocarbon feedstock containing asphaltenes and metals by contacting the feedstock with hydrogen and a bimodal catalyst which contains at least one metal, e.g., molybdenum, chromium and tungsten.
U.S. Pat. No. 4,411,770 describes a process for the hydroconversion of heavy hydrocarbon oils, wherein the catalyst comprises a crystalline zeolite component and a metallic hydrogenation component. The zeolites taught as being useful in this process include zeolites having a Constraint Index of 1 to 12 and Zeolite Beta.
Co-pending application Ser. No. 379,421, filed May 18, 1982, discloses a process and catalyst for simultaneously hydrocracking and dewaxing heavy hydrocarbon oils, such as vacuum gas oil. The catalyst system utilized is described as including 10 to 99 wt %, preferably 25 to 80 wt % Zeolite Beta, a porous matrix material, such as alumina, and a hydrogenation component derived from one or more metals of Groups VB, VIB or VIIIB of the Periodic Table (the Periodic Table referred to herein is the Table approved by IUPAC and the U.S. National Bureau of Standards, and is shown, for example, in the Table of the Fisher Scientific Company, Catalog No. 5-702-10, and is the Table of reference for this application).
U.S. Pat. No. 4,452,691 relates to a process for upgrading heavy oil to fuel products, comprising deasphalting the heavy oil with an oxygenated solvent and simultaneously converting the oxygenated solvent and deasphalted oil over a ZSM-5 type catalyst to produce gasoline and distillate boiling range hydrocarbons. The patent is hereby incorporated by reference.
An article, T. Y. Yan, Zeolite Based Catalyst for Hydrocracking, Ind. Eng. Chem. Process Des. Dev., 22, 154-160 (1983), relates to a zeolite/amorphous dual catalyst system developed for hydrocracked feeds with wide boiling range, in which the zeolite and amorphous catalyst operate complementally. The article is hereby incorporated by reference.
However, the prior art mentioned above has not combined, in a single stage operation, the hydrodewaxing and hydrotreating of petroleum resids using a catalyst, as described below, having at least three catalytic components, particularly to upgrade petroleum products to have fractions having pour points less than about 20.degree. F. and to have kinematic viscosity less than about 500 centistokes.